So after reading and searching the fourms I just wanted to confirm my choice is correct before moving forward.

I have an Axis A20.

I have the stock stereo and plan on going with 2 Rev-8's (maybe 10's) for the tower powered by Syn-4.

As for a battery, I have the stock () and plan on adding one for the stereo. I was thinking an Optima blue top (31M is correct option?). I have the battery isolator switch so it is fine to use two different batteries?

As for a charger, most suggest ProMariner 20? If I just have the 2 batteries so I need the 20 or will the 12 work fine?

I would pass on a Blue Top. A traditional wet cell Group-29 has almost 2x the Ah's at half the price. If a non-traditional mounting is needed, then an AGM like kinetic or Shuriken Will offer more Ah's at about the same cost as a battery with a colored top.

I think a 2 bank 12 amp charger would work just fine. I have two stereo batteries and a starting battery and I hook both banks up to the stereo batteries and everything is charged by the next day. When you are on the go, your starting battery is getting charged from the alternator, so you don't really have to worry about that battery unless you are using it to run your stereo equipment when you are just chilling.

Look into www.4xspower.com. I have run a pair of their D3100 series batteries for 3 years now and they have held up amazingly well. Yes, they are expensive, but they are well worth it. Just call down there and ask for Nathan Way. He'll help you find a local dealer and/or help hook you up. Because you just have battery boxes that are strapped to the floor in your ob compartment, it's nothing to remove them and reposition the little footers that keep the boxes in place to fit the larger size batteries. Most people could just buy one D3100 and use it as the stereo battery and be fine. For reference, last season, I ran 2 syn4's and a syn1 powering wetsounds interiors, 485's, and a XXX 12, and I could play the stereo pretty loud for a solid 4 hours with the boat off before one of the D3100's got low.

(Gryphon)
I looked into batteries for my stereo and ended up buying Kinetik HC 2400 x2. I bought one on Amazon.com and then later bought the second one on http://www.shopthedude.com/
It was on sale for $255. with shipping and tax it was barely under $300. They usually run for around $300 to $355 if you look hard enough.

Here is the Kinetik site. Good customer service too just for info. http://www.kinetikpower.com/2009/default.asp
Also bought a CTEK Multi US 25000 charger and love it. It has brought some of my old batteries back to life. Great charger. Not an on-board charger, but I just lay the charger in the boat while it charges at night. This is the charger that Kinetik recommended, because it is perfect for the specs of their batteries. So the told me.

Hello, I noticed your conversation regarding our batteries and wanted to offer some assistance. Optima batteries do not need special chargers. Any battery charger will work just fine to charge our batteries, but "gel" or "gel/AGM" settings should be avoided for all non-gel batteries, including Optimas, because they may not fully-charge non-gel batteries and could damage them over time. We do not recommend any specific brands of chargers or maintainers, but I know the ProMariner and CTEK folks are both very familiar with our products and the customer feedback we've received on their products has always been positive.

Maintaining our batteries with alternators will not damage them in any way. However, most alternators are designed to maintain batteries, not recharge deeply-discharged batteries. Asking that task of an alternator can lead to a cycle of dead batteries and jump-starts, until either the battery or alternator fails, regardless of the battery or alternator you are using.

As long as batteries are properly-isolated, dissimilar batteries can be used. However, anytime more than one battery is wired in series or parallel without isolation, they should be identical in age, size and type. Gryphon, the output you need from a charger will depend on how deeply you typically discharge your batteries and how much time your batteries can be charged in between use. If you only use your boat once a week and it sits idle the rest of the time, a relatively-small amp charger should have no trouble charging and maintaining your batteries. If you use your boat daily and deeply-discharge your batteries, you'll want a higher output unit. We recommend a maximum of 10 amps for our batteries.

The key to long battery life, regardless of brand, is proper voltage maintenance. When any battery is discharged below 12.4 volts and left to sit, sulfation begins to occur within the battery plates. This decreases both performance and lifespan. Fully-charged, our BlueTop batteries will measure about 13.0-13.2 volts, except for the 34M BlueTop, which will measure about 12.6-12.8 volts.

I would also caution anyone considering an online purchase to make sure they are dealing with an authorized online retailer. Any retailer from which you purchase a new Optima should provide warranty service for you, for the full duration of your warranty. However, there are some online retailers that do not. We strongly recommend that you find out the warranty procedures before making a purchase. If the seller’s procedure is to contact the manufacturer or if they do not provide a customer service phone number that they answer (not the Optima batteries customer service number) we recommend looking elsewhere.

In the event that product support service is needed, online purchases must be shipped back to the original seller and can take several days to be processed and returned.

I have a deep cycle Interstate group 24M SRM-24 550 CCA battery that came with the boat and is my starting battery (put in a fresh one this year). Now my stereo consisted of stock Kicker in-cabins and a Kicker ZX200.4 to power them along with a head unit.

This year I installed a pair of WS Pro80's with a Rockford Fosgate P500-2 amp along with an Exile ZLD to control zone volume. I picked up a Blue Sea system Perko switch and am presently looking at distribution blocks.

I was planning on just getting another Interstate SRM-24 and use it as my stereo battery. I've been reading posts on this forum, the moomba and supra forum and I just don't have a clue as to what I should do regarding a stereo battery!

I would at most be sitting and listening to the stereo for a couple of hours at a time (2-3 max). And I don't want to spend a ton of $$ on batteries.

Justin check out the interstate SRM 29. Bigger and better capacity than the 24 series. Price difference is like $10. We used one 29 for a syn 6, syn 4 and syn 2 last year with great results. http://www.batteriesexpressinc.com/i...roducts_id=320. Best price shipped I've found.

Justin, have you considered getting two 6v golf cart type batteries? Tons of amp hours compared to 2 Interstate group 24's. I'm not hating on Interstate batteries as I have 3 Interstate group 29's for my stereo and a group 24 for starting. I would have gone with two 6v batteries had I known I was going at add transom LEDs and extra lighting.

Justin, have you considered getting two 6v golf cart type batteries? Tons of amp hours compared to 2 Interstate group 24's. I'm not hating on Interstate batteries as I have 3 Interstate group 29's for my stereo and a group 24 for starting. I would have gone with two 6v batteries had I known I was going at add transom LEDs and extra lighting.

What's the difference between a 12v battery like the Interstate and 6v golf cart batteries? Again, I know nothing about this.

Don't use 6v batteries. You want the batteries to the same or close to the one that is already in the boat because it will allow it to charge at the same rate and will make it last longer.

There are several members on here that use a 6v battery bank and a traditional 12v starting battery and they work very well. There are also simple and inexpensive ways to make them work/charge and you get a ton of play time.

If I may quote from Brett (aka: polarbill) in a post on 6v batteries, "First of all wire anything associated with the stereo or LEDs over to the new stereo bank. If you do this you shouldn't ever really have have to charge the starting battery. Then you could probably get by with just a single bank charger. You need something better then a tender as your GC batteries are going to be really discharged. Maybe a smart charger around 20 amps should do. Find the setting on it recommended for lead acid batteries or that best matches the batteries specs."

If you are adding batteries to your boat, they should be properly-isolated from each other. As far as the type of battery for dedicated stereo use, I would encourage you to consider only batteries designed for deep-cycle use, which would include our BlueTops with light gray cases. I would also encourage you to check your voltage when you come off the water, to make sure your batteries are being properly-maintained by your boat's charging system.

As AJ suggested, if they need to be charged, it is better to fully-recharge them with a battery charger as soon as you come off the water, instead of waiting until right before the next time you head out or relying on your boat's charging system. If your boat stays on the water, making it hard to charge batteries with a battery charger, there are several solar and wind chargers on the market. However, I would encourage anyone going that route to make sure they are properly-regulated and won't overcharge your batteries, but will provide enough current to properly-maintain them.

If you are adding batteries to your boat, they should be properly-isolated from each other. As far as the type of battery for dedicated stereo use, I would encourage you to consider only batteries designed for deep-cycle use, which would include our BlueTops with light gray cases. I would also encourage you to check your voltage when you come off the water, to make sure your batteries are being properly-maintained by your boat's charging system.

As AJ suggested, if they need to be charged, it is better to fully-recharge them with a battery charger as soon as you come off the water, instead of waiting until right before the next time you head out or relying on your boat's charging system. If your boat stays on the water, making it hard to charge batteries with a battery charger, there are several solar and wind chargers on the market. However, I would encourage anyone going that route to make sure they are properly-regulated and won't overcharge your batteries, but will provide enough current to properly-maintain them.